[svn-r26198] INCOMPLETE, UNWORKING CODE

Commit progress through 1610 CST 2/17/15

21 files changed, 818 insertions, 349 deletions

diff --git a/src/H5Ddbg.c b/src/H5Ddbg.c
index a7c6dc1..adec71b 100644
--- a/src/H5Ddbg.c
+++ b/src/H5Ddbg.c
@@ -116,6 +116,8 @@ H5Ddebug(hid_t dset_id)
 	(void)H5D__chunk_dump_index(dset, H5AC_dxpl_id, stdout);
     else if(H5D_CONTIGUOUS == dset->shared->layout.type)
 	HDfprintf(stdout, "    %-10s %a\n", "Address:", dset->shared->layout.storage.u.contig.addr);
+    else if(H5D_VIRTUAL == dset->shared->layout.type)
+        HDassert(0 && "Not yet implemented...");//VDSINC
 
 done:
     FUNC_LEAVE_API(ret_value)
diff --git a/src/H5Dint.c b/src/H5Dint.c
index ee346f3..61a2ed7 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -1296,6 +1296,10 @@ H5D__open_oid(H5D_t *dataset, hid_t dapl_id, hid_t dxpl_id)
                     fill_prop->alloc_time = H5D_ALLOC_TIME_INCR;
                     break;
 
+                case H5D_VIRTUAL:
+                    fill_prop->alloc_time = H5D_ALLOC_TIME_INCR;
+                    break;
+
                 case H5D_LAYOUT_ERROR:
                 case H5D_NLAYOUTS:
                 default:
@@ -1310,7 +1314,8 @@ H5D__open_oid(H5D_t *dataset, hid_t dapl_id, hid_t dxpl_id)
     alloc_time_state = 0;
     if((dataset->shared->layout.type == H5D_COMPACT && fill_prop->alloc_time == H5D_ALLOC_TIME_EARLY)
             || (dataset->shared->layout.type == H5D_CONTIGUOUS && fill_prop->alloc_time == H5D_ALLOC_TIME_LATE)
-            || (dataset->shared->layout.type == H5D_CHUNKED && fill_prop->alloc_time == H5D_ALLOC_TIME_INCR))
+            || (dataset->shared->layout.type == H5D_CHUNKED && fill_prop->alloc_time == H5D_ALLOC_TIME_INCR)
+            || (dataset->shared->layout.type == H5D_VIRTUAL && fill_prop->alloc_time == H5D_ALLOC_TIME_INCR))
         alloc_time_state = 1;
 
     /* Set revised fill value properties, if they are different from the defaults */
@@ -1437,6 +1442,10 @@ H5D_close(H5D_t *dataset)
                 dataset->shared->layout.storage.u.compact.buf = H5MM_xfree(dataset->shared->layout.storage.u.compact.buf);
                 break;
 
+            case H5D_VIRTUAL:
+                /* Close datasets here?  VDSINC */
+                break;
+
             case H5D_LAYOUT_ERROR:
             case H5D_NLAYOUTS:
             default:
@@ -1681,6 +1690,10 @@ H5D__alloc_storage(const H5D_t *dset, hid_t dxpl_id, H5D_time_alloc_t time_alloc
                 } /* end if */
                 break;
 
+            case H5D_VIRTUAL:
+                /* No-op for now VDSINC */
+                break;
+
             case H5D_LAYOUT_ERROR:
             case H5D_NLAYOUTS:
             default:
@@ -1800,6 +1813,9 @@ H5D__init_storage(const H5D_t *dset, hbool_t full_overwrite, hsize_t old_dim[],
                 break;
             } /* end block */
 
+        case H5D_VIRTUAL:
+            /* No-op for now VDSINC */
+
         case H5D_LAYOUT_ERROR:
         case H5D_NLAYOUTS:
         default:
@@ -1856,6 +1872,10 @@ H5D__get_storage_size(H5D_t *dset, hid_t dxpl_id, hsize_t *storage_size)
             *storage_size = dset->shared->layout.storage.u.compact.size;
             break;
 
+        case H5D_VIRTUAL:
+            /* Just set to 0 until private data is implemented VDSINC */
+            *storage_size = 0;
+
         case H5D_LAYOUT_ERROR:
         case H5D_NLAYOUTS:
         default:
@@ -1894,6 +1914,7 @@ H5D__get_offset(const H5D_t *dset)
     switch(dset->shared->layout.type) {
         case H5D_CHUNKED:
         case H5D_COMPACT:
+        case H5D_VIRTUAL:
             break;
 
         case H5D_CONTIGUOUS:
diff --git a/src/H5Dlayout.c b/src/H5Dlayout.c
index 5929163..0dbe4db 100644
--- a/src/H5Dlayout.c
+++ b/src/H5Dlayout.c
@@ -174,6 +174,7 @@ H5D__layout_meta_size(const H5F_t *f, const H5O_layout_t *layout, hbool_t includ
             break;
 
         case H5D_VIRTUAL:
+            HDassert((layout->storage.u.virt.list_nused > 0) && "checking code coverage...");//VDSINC
             ret_value += H5F_SIZEOF_ADDR(f);    /* Address of global heap */
             ret_value += 4;                     /* Global heap index */
             break;
diff --git a/src/H5Doh.c b/src/H5Doh.c
index abf76d0..a688fe7 100644
--- a/src/H5Doh.c
+++ b/src/H5Doh.c
@@ -398,6 +398,9 @@ H5O__dset_bh_info(H5F_t *f, hid_t dxpl_id, H5O_t *oh, H5_ih_info_t *bh_info)
         if(H5D__chunk_bh_info(f, dxpl_id, &layout, &pline, &(bh_info->index_size)) < 0)
             HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't determine chunked dataset btree info")
     } /* end if */
+    else if(layout.type == H5D_VIRTUAL && H5D__virtual_is_space_alloc(&layout.storage)) {
+        HDassert(0 && "Not yet implemented...");//VDSINC
+    } /* end if */
 
     /* Check for External File List message in the object header */
     if((exists = H5O_msg_exists_oh(oh, H5O_EFL_ID)) < 0)
diff --git a/src/H5Dpkg.h b/src/H5Dpkg.h
index 1a659a1..ac6896f 100644
--- a/src/H5Dpkg.h
+++ b/src/H5Dpkg.h
@@ -174,14 +174,14 @@ typedef struct {
 } H5D_compact_storage_t;
 
 typedef struct {
-} H5D_virtual_storage_t;
+} H5D_virtual_storage_t;    /* Either fill out or remove VDSINC */
 
 typedef union H5D_storage_t {
     H5D_contig_storage_t contig; /* Contiguous information for dataset */
     H5D_chunk_storage_t chunk;  /* Chunk information for dataset */
     H5D_compact_storage_t compact; /* Compact information for dataset */
     H5O_efl_t   efl;            /* External file list information for dataset */
-    H5D_virtual_storage_t virtual; /* Virtual dataset information */
+    H5D_virtual_storage_t virt; /* Virtual dataset information */
 } H5D_storage_t;
 
 /* Typedef for raw data I/O operation info */
@@ -653,6 +653,13 @@ H5_DLL herr_t H5D__compact_copy(H5F_t *f_src, H5O_storage_compact_t *storage_src
     H5F_t *f_dst, H5O_storage_compact_t *storage_dst, H5T_t *src_dtype,
     H5O_copy_t *cpy_info, hid_t dxpl_id);
 
+/* Functions that operate on virtual dataset storage */
+H5_DLL herr_t H5D__virtual_copy(H5F_t *f_src,
+    const H5O_storage_virtual_t *storage_src, H5F_t *f_dst,
+    H5O_storage_virtual_t *storage_dst, H5T_t *dt_src, H5O_copy_t *cpy_info,
+    hid_t dxpl_id);
+H5_DLL hbool_t H5D__virtual_is_space_alloc(const H5O_storage_t *storage);
+
 /* Functions that operate on EFL (External File List)*/
 H5_DLL hbool_t H5D__efl_is_space_alloc(const H5O_storage_t *storage);
 H5_DLL herr_t H5D__efl_bh_info(H5F_t *f, hid_t dxpl_id, H5O_efl_t *efl,
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index 804afd1..11c9fac 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -106,6 +106,9 @@
 #define H5D_VLEN_FREE           NULL
 #define H5D_VLEN_FREE_INFO      NULL
 
+/* Default virtual dataset list size */
+#define H5D_VIRTUAL_DEF_LIST_SIZE 8
+
 
 /****************************/
 /* Library Private Typedefs */
@@ -176,8 +179,8 @@ H5_DLL herr_t H5D_chunk_idx_reset(H5O_storage_chunk_t *storage, hbool_t reset_ad
 
 /* Functions that operate on virtual storage */
 herr_t H5D_virtual_copy_layout(H5O_layout_t *layout);
-herr_t H5D__virtual_delete(H5F_t *f, hid_t dxpl_id,
-    const H5O_storage_t *storage);
+herr_t H5D_virtual_reset_layout(H5O_layout_t *layout);
+herr_t H5D_virtual_delete(H5F_t *f, hid_t dxpl_id, H5O_storage_t *storage);
 
 /* Functions that operate on indexed storage */
 H5_DLL herr_t H5D_btree_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE * stream,
diff --git a/src/H5Dpublic.h b/src/H5Dpublic.h
index 003e357..fb936d2 100644
--- a/src/H5Dpublic.h
+++ b/src/H5Dpublic.h
@@ -52,7 +52,7 @@ typedef enum H5D_layout_t {
     H5D_CONTIGUOUS	= 1,	/*the default				     */
     H5D_CHUNKED		= 2,	/*slow and fancy			     */
     H5D_VIRTUAL         = 3,    /*actual data is stored in other datasets     */
-    H5D_NLAYOUTS	= 3	/*this one must be last!		     */
+    H5D_NLAYOUTS	= 4	/*this one must be last!		     */
 } H5D_layout_t;
 
 /* Types of chunk index data structures */
diff --git a/src/H5Dvirtual.c b/src/H5Dvirtual.c
index 3053690..5e9decd 100644
--- a/src/H5Dvirtual.c
+++ b/src/H5Dvirtual.c
@@ -36,6 +36,7 @@
 #include "H5Eprivate.h"         /* Error handling                       */
 #include "H5Fprivate.h"         /* Files                                */
 #include "H5HGprivate.h"        /* Global Heaps                         */
+#include "H5MMprivate.h"        /* Memory management                    */
 #include "H5Oprivate.h"         /* Object headers                       */
 #include "H5Sprivate.h"         /* Dataspaces                           */
 
@@ -119,34 +120,35 @@ H5D_virtual_copy_layout(H5O_layout_t *layout)
     size_t          i;
     herr_t          ret_value = SUCCEED;
 
-    FUNC_ENTER_PACKAGE
+    FUNC_ENTER_NOAPI(FAIL)
 
     HDassert(layout);
+    HDassert(layout->type == H5D_VIRTUAL);
 
-    if(mesg->storage.u.virtual.list_nused > 0) {
+    if(layout->storage.u.virt.list_nused > 0) {
         HDassert(0 && "checking code coverage...");//VDSINC
-        HDassert(layout->storage.u.virtual.list);
+        HDassert(layout->storage.u.virt.list);
 
         /* Save original entry list for use as the "source" */
-        orig_list = layout->storage.u.virtual.list;
+        orig_list = layout->storage.u.virt.list;
 
         /* Allocate memory for the list */
-        if(NULL == (layout->storage.u.virtual.list = (H5O_storage_virtual_ent_t *)H5MM_calloc(layout->storage.u.virtual.list_nused * sizeof(H5O_storage_virtual_ent_t))))
+        if(NULL == (layout->storage.u.virt.list = (H5O_storage_virtual_ent_t *)H5MM_calloc(layout->storage.u.virt.list_nused * sizeof(H5O_storage_virtual_ent_t))))
             HGOTO_ERROR(H5E_DATASET, H5E_NOSPACE, FAIL, "unable to allocate memory for virtual dataset entry list")
-        layout->storage.u.virtual.list_nalloc = layout->storage.u.virtual.list_nused;
+        layout->storage.u.virt.list_nalloc = layout->storage.u.virt.list_nused;
 
         /* Copy the list entries */
-        for(i = 0; i < layout->storage.u.virtual.nused; i++) {
-            if(NULL == (layout->storage.u.virtual.list[i].source_file
-                    = HDstrdup(orig_list[i].source_file)))
+        for(i = 0; i < layout->storage.u.virt.list_nused; i++) {
+            if(NULL == (layout->storage.u.virt.list[i].source_file_name
+                    = HDstrdup(orig_list[i].source_file_name)))
                 HGOTO_ERROR(H5E_DATASET, H5E_RESOURCE, FAIL, "unable to duplicate source file name")
-            if(NULL == (layout->storage.u.virtual.list[i].source_dset
-                    = HDstrdup(orig_list[i].source_dset)))
+            if(NULL == (layout->storage.u.virt.list[i].source_dset_name
+                    = HDstrdup(orig_list[i].source_dset_name)))
                 HGOTO_ERROR(H5E_DATASET, H5E_RESOURCE, FAIL, "unable to duplicate source dataset name")
-            if(NULL == (layout->storage.u.virtual.list[i].source_select
+            if(NULL == (layout->storage.u.virt.list[i].source_select
                     = H5S_copy(orig_list[i].source_select, FALSE, TRUE)))
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTCOPY, FAIL, "unable to copy source selection")
-            if(NULL == (layout->storage.u.virtual.list[i].virtual_select
+            if(NULL == (layout->storage.u.virt.list[i].virtual_select
                     = H5S_copy(orig_list[i].virtual_select, FALSE, TRUE)))
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTCOPY, FAIL, "unable to copy virtual selection")
         } /* end for */
@@ -154,38 +156,74 @@ H5D_virtual_copy_layout(H5O_layout_t *layout)
     else {
         HDassert(0 && "checking code coverage...");//VDSINC
         /* Zero out other fields related to list, just to be sure */
-        layout->storage.u.virtual.list = NULL;
-        layout->storage.u.virtual.list_nalloc = 0;
+        layout->storage.u.virt.list = NULL;
+        layout->storage.u.virt.list_nalloc = 0;
     } /* end else */
 
 done:
     /* Release allocated resources on failure */
     if((ret_value < 0) && orig_list
-            && (orig_list != layout->storage.u.virtual.list)) {
-        /* Free the list entries */
-        for(i = 0; i < layout->storage.u.virtual.nused; i++) {
-            layout->storage.u.virtual.list[i].source_file = H5MM_xfree(layout->storage.u.virtual.list[i].source_file);
-            layout->storage.u.virtual.list[i].source_dset = H5MM_xfree(layout->storage.u.virtual.list[i].source_dset);
-            if(layout->storage.u.virtual.list[i].source_select
-                    && H5S_close(layout->storage.u.virtual.list[i].source_select) < 0)
-                HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release source selection")
-            mesg->storage.u.virtual.list[i].source_select = NULL;
-            if(layout->storage.u.virtual.list[i].virtual_select
-                    && H5S_close(layout->storage.u.virtual.list[i].virtual_select) < 0)
-                HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release virtual selection")
-            mesg->storage.u.virtual.list[i].virtual_select = NULL;
-        } /* end for */
-
-        /* Free the list */
-        layout->storage.u.virtual.list = H5MM_xfree(layout->storage.u.virtual.list);
-    } /* end if */
+            && (orig_list != layout->storage.u.virt.list))
+        if(H5D_virtual_reset_layout(layout) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "unable to reset virtual layout")
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D_virtual_copy_layout() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5D__virtual_delete
+ * Function:    H5D_virtual_reset_layout
+ *
+ * Purpose:     Frees internal structures in a virtual storage layout
+ *              message in memory.  This function is safe to use on
+ *              incomplete structures (for recovery from failure) provided
+ *              the internal structures are initialized with all bytes set
+ *              to 0.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Neil Fortner
+ *              February 11, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5D_virtual_reset_layout(H5O_layout_t *layout)
+{
+    size_t          i;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    HDassert(layout);
+    HDassert(layout->type == H5D_VIRTUAL);
+
+    /* Free the list entries.  Note we always attempt to free everything even in
+     * the case of a failure. */
+    for(i = 0; i < layout->storage.u.virt.list_nused; i++) {
+        layout->storage.u.virt.list[i].source_file_name = (char *)H5MM_xfree(layout->storage.u.virt.list[i].source_file_name);
+        layout->storage.u.virt.list[i].source_dset_name = (char *)H5MM_xfree(layout->storage.u.virt.list[i].source_dset_name);
+        if(layout->storage.u.virt.list[i].source_select
+                && H5S_close(layout->storage.u.virt.list[i].source_select) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release source selection")
+        layout->storage.u.virt.list[i].source_select = NULL;
+        if(layout->storage.u.virt.list[i].virtual_select
+                && H5S_close(layout->storage.u.virt.list[i].virtual_select) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release virtual selection")
+        layout->storage.u.virt.list[i].virtual_select = NULL;
+        /* Close dataset here?  VDSINC */
+    } /* end for */
+
+    /* Free the list */
+    layout->storage.u.virt.list = (H5O_storage_virtual_ent_t *)(layout->storage.u.virt.list);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5D_virtual_reset_layout() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5D_virtual_delete
  *
  * Purpose:     Delete the file space for a virtual dataset
  *
@@ -197,25 +235,30 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5D__virtual_delete(H5F_t *f, hid_t dxpl_id, const H5O_storage_t *storage)
+H5D_virtual_delete(H5F_t *f, hid_t dxpl_id, H5O_storage_t *storage)
 {
     herr_t ret_value = SUCCEED;   /* Return value */
 
-    FUNC_ENTER_PACKAGE
+    FUNC_ENTER_NOAPI(FAIL)
 
     /* check args */
     HDassert(f);
     HDassert(storage);
+    HDassert(storage->type == H5D_VIRTUAL);
 
     /* Need to add stuff for private data here VDSINC */
 
     /* Delete the global heap block */
-    if(H5HG_remove(f, dxpl_id, &(storage->u.virtual.serial_list_hobjid)) < 0)
+    if(H5HG_remove(f, dxpl_id, (H5HG_t *)&(storage->u.virt.serial_list_hobjid)) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "Unable to remove heap object")
 
+    /* Clear global heap ID in storage */
+    storage->u.virt.serial_list_hobjid.addr = HADDR_UNDEF;
+    storage->u.virt.serial_list_hobjid.idx = 0;
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5D__virtual_delete */
+} /* end H5D_virtual_delete */
 
 
 /*-------------------------------------------------------------------------
@@ -257,15 +300,18 @@ H5D__virtual_construct(H5F_t UNUSED *f, H5D_t UNUSED *dset)
  *-------------------------------------------------------------------------
  */
 hbool_t
-H5D__virtual_is_space_alloc(const H5O_storage_t UNUSED *storage)
+H5D__virtual_is_space_alloc(const H5O_storage_t *storage)
 {
     hbool_t ret_value;                  /* Return value */
 
     FUNC_ENTER_PACKAGE_NOERR
 
-    /* Need to decide what to do here.  For now just return true.  VDSINC */
+    HDassert(0 && "checking code coverage...");//VDSINC
+    /* Need to decide what to do here.  For now just return TRUE if the global
+     * heap block has been allocated.  VDSINC */
+    ret_value = storage->u.virt.serial_list_hobjid.addr != HADDR_UNDEF;
 
-    FUNC_LEAVE_NOAPI(TRUE)
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__virtual_is_space_alloc() */
 
 
@@ -381,8 +427,8 @@ H5D__virtual_flush(H5D_t UNUSED *dset, hid_t UNUSED dxpl_id)
  *-------------------------------------------------------------------------
  */
 herr_t
-H5D__virtual_copy(H5F_t UNUSED *f_src, const H5O_storage_contig_t UNUSED *storage_src,
-    H5F_t UNUSED *f_dst, H5O_storage_contig_t UNUSED *storage_dst, H5T_t UNUSED *dt_src,
+H5D__virtual_copy(H5F_t UNUSED *f_src, const H5O_storage_virtual_t UNUSED *storage_src,
+    H5F_t UNUSED *f_dst, H5O_storage_virtual_t UNUSED *storage_dst, H5T_t UNUSED *dt_src,
     H5O_copy_t UNUSED *cpy_info, hid_t UNUSED dxpl_id)
 {
     FUNC_ENTER_PACKAGE_NOERR
diff --git a/src/H5Olayout.c b/src/H5Olayout.c
index 2b12a97..0e43824 100644
--- a/src/H5Olayout.c
+++ b/src/H5Olayout.c
@@ -244,55 +244,62 @@ H5O_layout_decode(H5F_t *f, hid_t dxpl_id, H5O_t UNUSED *open_oh,
 
             case H5D_VIRTUAL:
                 /* Heap information */
-                H5F_addr_decode(f, &p, &(mesg->storage.u.virtual.serial_list_hobjid.addr));
-                UINT32DECODE(p, mesg->storage.u.virtual.serial_list_hobjid.idx);
+                H5F_addr_decode(f, &p, &(mesg->storage.u.virt.serial_list_hobjid.addr));
+                UINT32DECODE(p, mesg->storage.u.virt.serial_list_hobjid.idx);
 
                 /* Initialize other fields */
-                mesg->storage.u.virtual.list_nused = 0;
-                mesg->storage.u.virtual.list = NULL;
-                mesg->storage.u.virtual.list_nalloc = 0;
+                mesg->storage.u.virt.list_nused = 0;
+                mesg->storage.u.virt.list = NULL;
+                mesg->storage.u.virt.list_nalloc = 0;
 
                 /* Decode heap block if it exists */
-                if(mesg->storage.u.virtual.serial_list_hobjid.addr != HADDR_UNDEF) {
-                    uint8_t *heap_block_p;
+                if(mesg->storage.u.virt.serial_list_hobjid.addr != HADDR_UNDEF) {
+                    const uint8_t *heap_block_p;
                     size_t block_size = 0;
+                    size_t tmp_size;
                     hsize_t tmp_hsize;
                     uint32_t stored_chksum;
                     uint32_t computed_chksum;
                     size_t i;
 
                     /* Read heap */
-                    if(NULL == (heap_block = (uint8_t *)H5HG_read(f, dxpl_id, &(mesg->storage.u.virtual.serial_list_hobjid), NULL, &block_size)))
+                    if(NULL == (heap_block = (uint8_t *)H5HG_read(f, dxpl_id, &(mesg->storage.u.virt.serial_list_hobjid), NULL, &block_size)))
                         HGOTO_ERROR(H5E_OHDR, H5E_READERROR, NULL, "Unable to read global heap block")
 
-                    heap_block_p = heap_block;
+                    heap_block_p = (const uint8_t *)heap_block;
 
                     /* Number of entries */
                     H5F_DECODE_LENGTH(f, heap_block_p, tmp_hsize)
 
                     /* Allocate entry list */
-                    if(NULL == (mesg->storage.u.virtual.list = (H5O_storage_virtual_ent_t *)H5MM_malloc((size_t)tmp_hsize * sizeof(H5O_storage_virtual_ent_t))))
+                    if(NULL == (mesg->storage.u.virt.list = (H5O_storage_virtual_ent_t *)H5MM_calloc((size_t)tmp_hsize * sizeof(H5O_storage_virtual_ent_t))))
                         HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, NULL, "unable to allocate heap block")
-                    mesg->storage.u.virtual.list_nalloc = (size_t)tmp_hsize;
-                    mesg->storage.u.virtual.list_nused = (size_t)tmp_hsize;
+                    mesg->storage.u.virt.list_nalloc = (size_t)tmp_hsize;
+                    mesg->storage.u.virt.list_nused = (size_t)tmp_hsize;
 
                     /* Decode each entry */
-                    for(i = 0; i < mesg->storage.u.virtual.list_nused; i++) {
+                    for(i = 0; i < mesg->storage.u.virt.list_nused; i++) {
                         /* Source file name */
-                        if(NULL == (mesg->storage.u.virtual.list[i].source_file = HDstrdup(heap_block_p)))
-                            HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, NULL, "unable to duplicate source file name")
-                        heap_block_p += HDstrlen(heap_block_p) + 1;
+                        tmp_size = HDstrlen((const char *)heap_block_p) + 1;
+                        if(NULL == (mesg->storage.u.virt.list[i].source_file_name = (char *)H5MM_malloc(tmp_size)))
+                            HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, NULL, "unable to allocate memory for source file name")
+                        (void)HDmemcpy(mesg->storage.u.virt.list[i].source_file_name, heap_block_p, tmp_size);
+                        heap_block_p += tmp_size;
 
                         /* Source dataset name */
-                        if(NULL == (mesg->storage.u.virtual.list[i].source_dset = HDstrdup(heap_block_p)))
-                            HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, NULL, "unable to duplicate source dataset name")
-                        heap_block_p += HDstrlen(heap_block_p) + 1;
+                        tmp_size = HDstrlen((const char *)heap_block_p) + 1;
+                        if(NULL == (mesg->storage.u.virt.list[i].source_dset_name = (char *)H5MM_malloc(tmp_size)))
+                            HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, NULL, "unable to allocate memory for source dataset name")
+                        (void)HDmemcpy(mesg->storage.u.virt.list[i].source_dset_name, heap_block_p, tmp_size);
+                        heap_block_p += tmp_size;
 
                         /* Source selection */
-                        H5S_SELECT_DESERIALIZE(&(mesg->storage.u.virtual.list[i].source_select), &heap_block_p)
+                        if(H5S_SELECT_DESERIALIZE(&(mesg->storage.u.virt.list[i].source_select), &heap_block_p) < 0)
+                            HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "can't decode source space selection")
 
                         /* Virtual selection */
-                        H5S_SELECT_SERIALIZE(&(mesg->storage.u.virtual.list[i].virtual_select), &heap_block_p)
+                        if(H5S_SELECT_DESERIALIZE(&(mesg->storage.u.virt.list[i].virtual_select), &heap_block_p) < 0)
+                            HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "can't decode virtual space selection")
                     } /* end for */
 
                     /* Read stored checksum */
@@ -304,6 +311,10 @@ H5O_layout_decode(H5F_t *f, hid_t dxpl_id, H5O_t UNUSED *open_oh,
                     /* Verify checksum */
                     if(stored_chksum != computed_chksum)
                         HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, NULL, "incorrect metadata checksum for global heap block")
+
+                    /* Verify that the heap block size is correct */
+                    if((size_t)(heap_block_p - heap_block) != block_size)
+                        HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, NULL, "incorrect heap block size")
                 } /* end if */
 
                 break;
@@ -322,10 +333,12 @@ done:
     if(ret_value == NULL)
         if(mesg) {
             if(mesg->type == H5D_VIRTUAL)
-                mesg->
+                if(H5D_virtual_reset_layout(mesg) < 0)
+                    HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, NULL, "unable to reset virtual layout")
             mesg = H5FL_FREE(H5O_layout_t, mesg);
+        } /* end if */
 
-    heap_block = H5MM_xfree(heap_block);
+    heap_block = (uint8_t *)H5MM_xfree(heap_block);
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5O_layout_decode() */
@@ -366,6 +379,7 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
 {
     const H5O_layout_t     *mesg = (const H5O_layout_t *) _mesg;
     uint8_t                *heap_block = NULL;
+    size_t                  *str_size = NULL;
     unsigned               u;
     herr_t ret_value = SUCCEED;   /* Return value */
 
@@ -421,8 +435,8 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
             /* Note that we assume here that the contents of the heap block
              * cannot change!  If this ever stops being the case we must change
              * this code to allow overwrites of the heap block.  -NAF */
-            if((mesg->storage.u.virtual.serial_list_hobjid.addr == HADDR_UNDEF)
-                    && (mesg->storage.u.virtual.list_nused > 0)) {
+            if((mesg->storage.u.virt.serial_list_hobjid.addr == HADDR_UNDEF)
+                    && (mesg->storage.u.virt.list_nused > 0)) {
                 uint8_t *heap_block_p;
                 size_t block_size;
                 hssize_t select_serial_size;
@@ -430,6 +444,10 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
                 uint32_t chksum;
                 size_t i;
 
+                /* Allocate array for caching results of strlen */
+                if(NULL == (str_size = (size_t *)H5MM_malloc(2 * mesg->storage.u.virt.list_nused *sizeof(size_t))))
+                    HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, FAIL, "unable to allocate string length array")
+
                 /*
                  * Calculate heap block size
                  */
@@ -437,25 +455,27 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
                 block_size = H5F_SIZEOF_SIZE(f);
 
                 /* Calculate size of each entry */
-                for(i = 0; i < mesg->storage.u.virtual.list_nused; i++) {
-                    HDassert(mesg->storage.u.virtual.list[i].source_file);
-                    HDassert(mesg->storage.u.virtual.list[i].source_dset);
-                    HDassert(mesg->storage.u.virtual.list[i].source_select);
-                    HDassert(mesg->storage.u.virtual.list[i].virtual_select);
+                for(i = 0; i < mesg->storage.u.virt.list_nused; i++) {
+                    HDassert(mesg->storage.u.virt.list[i].source_file_name);
+                    HDassert(mesg->storage.u.virt.list[i].source_dset_name);
+                    HDassert(mesg->storage.u.virt.list[i].source_select);
+                    HDassert(mesg->storage.u.virt.list[i].virtual_select);
 
                     /* Source file name */
-                    block_size += HDstrlen(mesg->storage.u.virtual.list[i].source_file) + (size_t)1;
+                    str_size[2 * i] = HDstrlen(mesg->storage.u.virt.list[i].source_file_name) + (size_t)1;
+                    block_size += str_size[2 * i];
 
                     /* Source dset name */
-                    block_size += HDstrlen(mesg->storage.u.virtual.list[i].source_dset) + (size_t)1;
+                    str_size[(2 * i) + 1] = HDstrlen(mesg->storage.u.virt.list[i].source_dset_name) + (size_t)1;
+                    block_size += str_size[(2 * i) + 1];
 
                     /* Source selection */
-                    if((select_serial_size = H5S_SELECT_SERIAL_SIZE(mesg->storage.u.virtual.list[i].source_select)) < 0)
+                    if((select_serial_size = H5S_SELECT_SERIAL_SIZE(mesg->storage.u.virt.list[i].source_select)) < 0)
                         HGOTO_ERROR(H5E_OHDR, H5E_CANTENCODE, FAIL, "unable to check dataspace selection size")
                     block_size += (size_t)select_serial_size;
 
                     /* Virtual dataset selection */
-                    if((select_serial_size = H5S_SELECT_SERIAL_SIZE(mesg->storage.u.virtual.list[i].virtual_select)) < 0)
+                    if((select_serial_size = H5S_SELECT_SERIAL_SIZE(mesg->storage.u.virt.list[i].virtual_select)) < 0)
                         HGOTO_ERROR(H5E_OHDR, H5E_CANTENCODE, FAIL, "unable to check dataspace selection size")
                     block_size += (size_t)select_serial_size;
                 } /* end for */
@@ -464,7 +484,7 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
                 block_size += 4;
 
                 /* Allocate heap block */
-                if(NULL == (heap_block = (uint8_t *)H5MM_malloc((size_t)mesg->storage.u.virtual.serial_list_size)))
+                if(NULL == (heap_block = (uint8_t *)H5MM_malloc(block_size)))
                     HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, FAIL, "unable to allocate heap block")
 
                 /*
@@ -473,26 +493,26 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
                 heap_block_p = heap_block;
 
                 /* Number of entries */
-                tmp_hsize = (hsize_t)mesg->storage.u.virtual.list_nused;
+                tmp_hsize = (hsize_t)mesg->storage.u.virt.list_nused;
                 H5F_ENCODE_LENGTH(f, heap_block_p, tmp_hsize)
 
                 /* Encode each entry */
-                for(i = 0; i < mesg->storage.u.virtual.list_nused; i++) {
+                for(i = 0; i < mesg->storage.u.virt.list_nused; i++) {
                     /* Source file name */
-                    (void)HDstrcpy(heap_block_p, mesg->storage.u.virtual.list[i].source_file);
-                    heap_block_p += HDstrlen(heap_block_p) + 1;
+                    (void)HDstrcpy((char *)heap_block_p, mesg->storage.u.virt.list[i].source_file_name);
+                    heap_block_p += str_size[2 * i];
 
                     /* Source dataset name */
-                    (void)HDstrcpy(heap_block_p, mesg->storage.u.virtual.list[i].source_dset);
-                    heap_block_p += HDstrlen(heap_block_p) + 1;
+                    (void)HDstrcpy((char *)heap_block_p, mesg->storage.u.virt.list[i].source_dset_name);
+                    heap_block_p += str_size[(2 * i) + 1];
 
                     /* Source selection */
-                    if(H5S_SELECT_SERIALIZE(mesg->storage.u.virtual.list[i].source_select, &heap_block_p) < 0)
-                        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "Unable to serialize selection")
+                    if(H5S_SELECT_SERIALIZE(mesg->storage.u.virt.list[i].source_select, &heap_block_p) < 0)
+                        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to serialize source selection")
 
                     /* Virtual selection */
-                    if(H5S_SELECT_SERIALIZE(mesg->storage.u.virtual.list[i].virtual_select, &heap_block_p) < 0)
-                        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "Unable to serialize selection")
+                    if(H5S_SELECT_SERIALIZE(mesg->storage.u.virt.list[i].virtual_select, &heap_block_p) < 0)
+                        HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to serialize virtual selection")
                 } /* end for */
 
                 /* Checksum */
@@ -501,13 +521,15 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
 
                 /* Insert block into global heap */
                 /* Casting away const OK  --NAF */
-                if(H5HG_insert(f, H5AC_ind_dxpl_id, block_size, heap_block, &((H5O_layout_t *)mesg)->storage.u.virtual.serial_list_hobjid) < 0)
+                if(H5HG_insert(f, H5AC_ind_dxpl_id, block_size, heap_block, &((H5O_layout_t *)mesg)->storage.u.virt.serial_list_hobjid) < 0)
                     HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "unable to insert virtual dataset heap block")
             } /* end if */
 
+            HDassert((mesg->storage.u.virt.list_nused > 0) && "checking code coverage...");//VDSINC
+
             /* Heap information */
-            H5F_addr_encode(f, &p, mesg->storage.u.virtual.serial_list_hobjid.addr);
-            UINT32ENCODE(p, mesg->storage.u.virtual.serial_list_hobjid.idx);
+            H5F_addr_encode(f, &p, mesg->storage.u.virt.serial_list_hobjid.addr);
+            UINT32ENCODE(p, mesg->storage.u.virt.serial_list_hobjid.idx);
 
             break;
 
@@ -518,7 +540,8 @@ H5O_layout_encode(H5F_t *f, hbool_t UNUSED disable_shared, uint8_t *p, const voi
     } /* end switch */
 
 done:
-    heap_block = H5MM_xfree(heap_block);
+    heap_block = (uint8_t *)H5MM_xfree(heap_block);
+    str_size = (size_t *)H5MM_xfree(str_size);
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5O_layout_encode() */
@@ -573,9 +596,11 @@ H5O_layout_copy(const void *_mesg, void *_dest)
 	H5D_chunk_idx_reset(&dest->storage.u.chunk, FALSE);
 
     /* Deep copy the entry list for virtual datasets */
-    if(mesg->type == H5D_VIRTUAL)
+    if(mesg->type == H5D_VIRTUAL) {
+        HDassert((mesg->storage.u.virt.list_nused > 0) && "checking code coverage...");//VDSINC
         if(H5D_virtual_copy_layout(dest) < 0)
             HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, NULL, "unable to copy virtual layout")
+    } //VDSINC
 
     /* Set return value */
     ret_value = dest;
@@ -650,28 +675,10 @@ H5O_layout_reset(void *_mesg)
         /* Free the compact storage buffer */
         if(H5D_COMPACT == mesg->type)
             mesg->storage.u.compact.buf = H5MM_xfree(mesg->storage.u.compact.buf);
-
-        /* Free the virtual entry list */
-        if(H5D_VIRTUAL == mesg->type) {
-            if(mesg->storage.u.virtual.list_nused > 0) {
-                size_t  i;
-                HDassert(mesg->storage.u.virtual.list);
-
-                /* Free the list entries */
-                for(i = 0; i < mesg->storage.u.virtual.nused; i++) {
-                    mesg->storage.u.virtual.list[i].source_file = H5MM_xfree(mesg->storage.u.virtual.list[i].source_file);
-                    mesg->storage.u.virtual.list[i].source_dset = H5MM_xfree(mesg->storage.u.virtual.list[i].source_dset);
-                    if(H5S_close(mesg->storage.u.virtual.list[i].source_select) < 0)
-                        HGOTO_ERROR(H5E_OHDR, H5E_CLOSEERROR, FAIL, "unable to release source selection")
-                    mesg->storage.u.virtual.list[i].source_select = NULL;
-                    if(H5S_close(mesg->storage.u.virtual.list[i].virtual_select) < 0)
-                        HGOTO_ERROR(H5E_OHDR, H5E_CLOSEERROR, FAIL, "unable to release virtual selection")
-                    mesg->storage.u.virtual.list[i].virtual_select = NULL;
-                } /* end for */
-
-                /* Free the list */
-                mesg->storage.u.virtual.list = H5MM_xfree(mesg->storage.u.virtual.list);
-            } /* end if */
+        else if(H5D_VIRTUAL == mesg->type)
+            /* Free the virtual entry list */
+            if(H5D_virtual_reset_layout(mesg) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to reset virtual layout")
 
         /* Reset the message */
         mesg->type = H5D_CONTIGUOUS;
@@ -761,7 +768,7 @@ H5O_layout_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, void *_mesg)
         case H5D_VIRTUAL:       /* Virtual dataset */
             HDassert(0 && "checking code coverage...");//VDSINC
             /* Free the file space virtual dataset */
-            if(H5D__virtual_delete(f, dxpl_id, &mesg->storage) < 0)
+            if(H5D_virtual_delete(f, dxpl_id, &mesg->storage) < 0)
                 HGOTO_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to free raw data")
             break;
 
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index b3d6237..ac8d02f 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -37,6 +37,7 @@
 /* Private headers needed by this file */
 #include "H5ACprivate.h"        /* Metadata cache                       */
 #include "H5Fprivate.h"		/* File access				*/
+#include "H5HGprivate.h"        /* Global Heaps                         */
 #include "H5SLprivate.h"	/* Skip lists				*/
 #include "H5Tprivate.h"		/* Datatype functions			*/
 #include "H5Zprivate.h"         /* I/O pipeline filters			*/
@@ -413,21 +414,21 @@ typedef struct H5O_storage_compact_t {
 
 typedef struct H5O_storage_virtual_ent_t {
     /* Stored */
-    char        *source_file;
-    char        *source_dset;
-    H5S_t       *source_select;
-    H5S_t       *virtual_select;
+    char        *source_file_name;      /* Source file name used for virtual dataset mapping */
+    char        *source_dset_name;      /* Source dataset name used for virtual dataset mapping */
+    struct H5S_t *source_select;        /* Selection in the source dataset for mapping */
+    struct H5S_t *virtual_select;       /* Selection in the virtual dataset that is mapped to source_select */
 
     /* Not stored */
-    H5D_t       *source_dset;
+    struct H5D_t *source_dset;          /* Source dataset */
 } H5O_storage_virtual_ent_t;
 
 typedef struct H5O_storage_virtual_t {
     /* Stored in message */
-    H5HG_t      serial_list_hobjid;
+    H5HG_t      serial_list_hobjid;     /* Global heap ID for the list of virtual mapping entries stored on disk */
 
     /* Stored in heap */
-    size_t      list_nused;             /* Number of slots used               */
+    size_t      list_nused;             /* Number of array elements used in list    */
     H5O_storage_virtual_ent_t *list;    /* Array of virtual dataset mapping entries */
 
     /* Not stored */
@@ -440,7 +441,7 @@ typedef struct H5O_storage_t {
         H5O_storage_contig_t contig;    /* Information for contiguous storage */
         H5O_storage_chunk_t chunk;      /* Information for chunked storage    */
         H5O_storage_compact_t compact;  /* Information for compact storage    */
-        H5O_storage_virtual_t virtual;  /* Information for virtual storage    */
+        H5O_storage_virtual_t virt;     /* Information for virtual storage    */
     } u;
 } H5O_storage_t;
 
diff --git a/src/H5Pdcpl.c b/src/H5Pdcpl.c
index e9bd9bf..6abe17d 100644
--- a/src/H5Pdcpl.c
+++ b/src/H5Pdcpl.c
@@ -61,8 +61,8 @@
 #define H5D_DEF_STORAGE_COMPACT  {H5D_COMPACT, { .compact = H5D_DEF_STORAGE_COMPACT_INIT }}
 #define H5D_DEF_STORAGE_CONTIG   {H5D_CONTIGUOUS, { .contig = H5D_DEF_STORAGE_CONTIG_INIT }}
 #define H5D_DEF_STORAGE_CHUNK    {H5D_CHUNKED, { .chunk = H5D_DEF_STORAGE_CHUNK_INIT }}
-#define H5D_DEF_STORAGE_VIRTUAL  {H5D_CHUNKED, { .chunk = H5D_DEF_STORAGE_CHUNK_INIT }}
-#define H5D_DEF_LAYOUT_COMPACT  {H5D_COMPACT, H5O_LAYOUT_VERSION_3, NULL, {H5D_DEF_LAYOUT_CHUNK_INIT}, H5D_DEF_STORAGE_VIRTUAL}
+#define H5D_DEF_STORAGE_VIRTUAL  {H5D_CHUNKED, { .virt = H5D_DEF_STORAGE_VIRTUAL_INIT }}
+#define H5D_DEF_LAYOUT_COMPACT  {H5D_COMPACT, H5O_LAYOUT_VERSION_3, NULL, {H5D_DEF_LAYOUT_CHUNK_INIT}, H5D_DEF_STORAGE_COMPACT}
 #define H5D_DEF_LAYOUT_CONTIG   {H5D_CONTIGUOUS, H5O_LAYOUT_VERSION_3, NULL, {H5D_DEF_LAYOUT_CHUNK_INIT}, H5D_DEF_STORAGE_CONTIG}
 #define H5D_DEF_LAYOUT_CHUNK    {H5D_CHUNKED, H5O_LAYOUT_VERSION_3, NULL, {H5D_DEF_LAYOUT_CHUNK_INIT}, H5D_DEF_STORAGE_CHUNK}
 #define H5D_DEF_LAYOUT_VIRTUAL  {H5D_VIRTUAL, H5O_LAYOUT_VERSION_3, NULL, {H5D_DEF_LAYOUT_CHUNK_INIT}, H5D_DEF_STORAGE_VIRTUAL}
@@ -136,7 +136,10 @@ static herr_t H5P__dcrt_close(hid_t dxpl_id, void *close_data);
 /* Property callbacks */
 static herr_t H5P__dcrt_layout_enc(const void *value, void **pp, size_t *size);
 static herr_t H5P__dcrt_layout_dec(const void **pp, void *value);
+static herr_t H5P__dcrt_layout_del(hid_t prop_id, const char *name, size_t size, void *value);
+static herr_t H5P__dcrt_layout_copy(const char *name, size_t size, void *value);
 static int H5P__dcrt_layout_cmp(const void *value1, const void *value2, size_t size);
+static herr_t H5P__dcrt_layout_close(const char *name, size_t size, void *value);
 static herr_t H5P__fill_value_enc(const void *value, void **pp, size_t *size);
 static herr_t H5P__fill_value_dec(const void **pp, void *value);
 static herr_t H5P__dcrt_ext_file_list_enc(const void *value, void **pp, size_t *size);
@@ -324,6 +327,10 @@ H5P__dcrt_copy(hid_t dst_plist_id, hid_t src_plist_id, void UNUSED *copy_data)
             dst_layout.storage.u.chunk.ops = NULL;
             break;
 
+        case H5D_VIRTUAL:
+            dst_layout.storage.u.virt.serial_list_hobjid.addr = HADDR_UNDEF;
+            dst_layout.storage.u.virt.serial_list_hobjid.idx = 0;
+
         case H5D_LAYOUT_ERROR:
         case H5D_NLAYOUTS:
         default:
@@ -568,7 +575,7 @@ done:
  * Purpose:     Frees memory used to store the layout property
  *
  * Return:      Success:        Non-negative
- *              Failure:        Never fails
+ *              Failure:        Negative
  *
  * Programmer:  Neil Fortner
  *              Tuesday, Feb 10, 2015
@@ -578,13 +585,21 @@ done:
 static herr_t
 H5P__dcrt_layout_del(hid_t UNUSED prop_id, const char UNUSED *name, size_t UNUSED size, void *value)
 {
-    FUNC_ENTER_STATIC_NOERR
+    H5O_layout_t *layout = (H5O_layout_t *)value; /* Create local aliases for values */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-    HDassert(value);
+    FUNC_ENTER_STATIC
 
-    (void)H5O_msg_free(H5O_LAYOUT_ID, value)
+    /* Sanity check */
+    HDassert(layout);
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+    /* Reset the old layout befopre overwriting it if necessary */
+    if(layout->type == H5D_VIRTUAL)
+        if(H5D_virtual_reset_layout(layout) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "unable to reset virtual layout")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5P__dcrt_layout_del() */
 
 
@@ -604,12 +619,12 @@ H5P__dcrt_layout_del(hid_t UNUSED prop_id, const char UNUSED *name, size_t UNUSE
 static herr_t
 H5P__dcrt_layout_copy(const char UNUSED *name, size_t UNUSED size, void *value)
 {
-    H5O_layout_t    *layout;
+    H5O_layout_t    *layout = (H5O_layout_t *)value; /* Create local aliases for values */
     herr_t          ret_value = SUCCEED;
 
     FUNC_ENTER_STATIC
 
-    HDassert(value);
+    HDassert(layout);
 
     layout = (H5O_layout_t *)value;
 
@@ -703,7 +718,7 @@ done:
  * Purpose:     Frees memory used to store the layout property
  *
  * Return:      Success:        Non-negative
- *              Failure:        Never fails
+ *              Failure:        Negative
  *
  * Programmer:  Neil Fortner
  *              Tuesday, Feb 10, 2015
@@ -713,13 +728,21 @@ done:
 static herr_t
 H5P__dcrt_layout_close(const char UNUSED *name, size_t UNUSED size, void *value)
 {
-    FUNC_ENTER_STATIC_NOERR
+    H5O_layout_t *layout = (H5O_layout_t *)value; /* Create local aliases for values */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-    HDassert(value);
+    FUNC_ENTER_STATIC
 
-    (void)H5O_msg_free(H5O_LAYOUT_ID, value)
+    /* Sanity check */
+    HDassert(layout);
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+    /* Reset the old layout befopre overwriting it if necessary */
+    if(layout->type == H5D_VIRTUAL)
+        if(H5D_virtual_reset_layout(layout) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "unable to reset virtual layout")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5P__dcrt_layout_close() */
 
 
@@ -1217,6 +1240,7 @@ done:
 static herr_t
 H5P__set_layout(H5P_genplist_t *plist, const H5O_layout_t *layout)
 {
+    H5O_layout_t old_layout;            /* Layout propertry already on list */
     unsigned alloc_time_state;          /* State of allocation time property */
     herr_t ret_value = SUCCEED;         /* return value */
 
@@ -1263,6 +1287,17 @@ H5P__set_layout(H5P_genplist_t *plist, const H5O_layout_t *layout)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set space allocation time")
     } /* end if */
 
+    /* Get the old layout */
+    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &old_layout) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get layout")
+
+    /* Reset the old layout before overwriting it if necessary */
+    if(old_layout.type == H5D_VIRTUAL) {
+        HDassert((layout->storage.u.virt.list_nused > 0) && "checking code coverage...");//VDSINC
+        if(H5D_virtual_reset_layout(&old_layout) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "unable to reset virtual layout")
+    } //VDSINC
+
     /* Set layout value */
     if(H5P_set(plist, H5D_CRT_LAYOUT_NAME, layout) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't set layout")
@@ -1278,7 +1313,8 @@ done:
  *
  * Purpose:   Set the default layout information for the various types of
  *              dataset layouts
- *
+
+ 
  * Return:    Non-negative on success/Negative on failure
  *
  * Programmer:	Quincey Koziol
@@ -1300,7 +1336,7 @@ H5P__init_def_layout(void)
     H5D_def_layout_compact_g.storage.u.compact = def_store_compact;
     H5D_def_layout_chunk_g.u.chunk = def_layout_chunk;
     H5D_def_layout_chunk_g.storage.u.chunk = def_store_chunk;
-    H5D_def_layout_virtual_g.storage.u.virtual = def_store_virtual;
+    H5D_def_layout_virtual_g.storage.u.virt = def_store_virtual;
 
     /* Note that we've initialized the default values */
     H5P_dcrt_def_layout_init_g = TRUE;
@@ -1579,6 +1615,354 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5Pset_virtual
+ *
+ * Purpose:     VDSINC
+ *
+ *              As a side effect, the layout method is changed to
+ *              H5D_VIRTUAL.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Neil Fortner
+ *              Friday, February  13, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_virtual(hid_t dcpl_id, hid_t vspace_id, const char *src_file_name,
+    const char *src_dset_name, hid_t src_space_id)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    H5O_layout_t layout;        /* Layout information for setting chunk info */
+    H5S_t *vspace;              /* Virtual dataset space selection */
+    H5S_t *src_space;           /* Source dataset space selection */
+    hbool_t new_layout = FALSE; /* Whether we are adding a new virtual layout message to plist */
+    hbool_t adding_entry = FALSE; /* Whether we are in the middle of adding an entry */
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE5("e", "ii*s*si", dcpl_id, vspace_id, src_file_name, src_dset_name,
+             src_space_id);
+
+    /* Check arguments */
+    if(!src_file_name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "source file name not provided")
+    if(!src_dset_name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, FAIL, "source dataset name not provided")
+    if(NULL == (vspace = (H5S_t *)H5I_object_verify(vspace_id, H5I_DATASPACE)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataspace")
+    if(NULL == (src_space = (H5S_t *)H5I_object_verify(src_space_id, H5I_DATASPACE)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataspace")
+
+#ifndef H5_HAVE_C99_DESIGNATED_INITIALIZER
+    /* If the compiler doesn't support C99 designated initializers, check if
+     *  the default layout structs have been initialized yet or not.  *ick* -QAK
+     */
+    if(!H5P_dcrt_def_layout_init_g)
+        if(H5P__init_def_layout() < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't initialize default layout info")
+#endif /* H5_HAVE_C99_DESIGNATED_INITIALIZER */
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Get the current layout */
+    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &layout) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get layout")
+
+    /* If the layout was not already virtual, Start with default virtual layout.
+     * Otherwise, add the mapping to the current list. */
+    if(layout.type != H5D_VIRTUAL) {
+        new_layout = TRUE;
+        HDmemcpy(&layout, &H5D_def_layout_virtual_g, sizeof(H5D_def_layout_virtual_g));
+    } /* end if */
+
+    /* Expand list if necessary */
+    if(layout.storage.u.virt.list_nalloc == 0) {
+        /* Allocate initial entry list */
+        if(NULL == (layout.storage.u.virt.list = (H5O_storage_virtual_ent_t *)H5MM_calloc(H5D_VIRTUAL_DEF_LIST_SIZE * sizeof(H5O_storage_virtual_ent_t))))
+            HGOTO_ERROR(H5E_PLIST, H5E_RESOURCE, FAIL, "can't allocate virtual dataset mapping list")
+    } /* end if */
+    else if(layout.storage.u.virt.list_nused
+            == layout.storage.u.virt.list_nalloc) {
+        HDassert((layout.storage.u.virt.list_nused > 0) && "checking code coverage...");//VDSINC
+        /* Double size of entry list.  Make sure to zero out new memory. */
+        if(NULL == (layout.storage.u.virt.list = (H5O_storage_virtual_ent_t *)H5MM_realloc(layout.storage.u.virt.list, (size_t)2 * layout.storage.u.virt.list_nalloc * sizeof(H5O_storage_virtual_ent_t))))
+            HGOTO_ERROR(H5E_PLIST, H5E_RESOURCE, FAIL, "can't reallocate virtual dataset mapping list")
+        (void)HDmemset(layout.storage.u.virt.list + layout.storage.u.virt.list_nalloc, 0, layout.storage.u.virt.list_nalloc * sizeof(H5O_storage_virtual_ent_t));
+        layout.storage.u.virt.list_nalloc *= (size_t)2;
+    } /* end if */
+
+    /* Add virtual dataset mapping entry */
+    if(NULL == (layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_file_name = HDstrdup(src_file_name)))
+        HGOTO_ERROR(H5E_PLIST, H5E_RESOURCE, FAIL, "can't duplicate source file name")
+    adding_entry = TRUE;
+    if(NULL == (layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_dset_name = HDstrdup(src_dset_name)))
+        HGOTO_ERROR(H5E_PLIST, H5E_RESOURCE, FAIL, "can't duplicate source file name")
+    if(NULL == (layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_select = H5S_copy(src_space, FALSE, TRUE)))
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTCOPY, FAIL, "unable to copy source selection")
+    if(NULL == (layout.storage.u.virt.list[layout.storage.u.virt.list_nused].virtual_select = H5S_copy(vspace, FALSE, TRUE)))
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTCOPY, FAIL, "unable to copy virtual selection")
+    layout.storage.u.virt.list_nused++;
+    adding_entry = FALSE;
+
+    /* Set chunk information in property list if we are adding a new layout */
+    if(new_layout)
+        if(H5P__set_layout(plist, &layout) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set layout")
+
+done:
+    if(adding_entry) {
+        HDassert(ret_value < 0);
+
+        /* Free incomplete entry */
+        layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_file_name = (char *)H5MM_xfree(layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_file_name);
+        layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_dset_name = (char *)H5MM_xfree(layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_dset_name);
+        if(layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_select
+                && H5S_close(layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_select) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release source selection")
+        layout.storage.u.virt.list[layout.storage.u.virt.list_nused].source_select = NULL;
+        HDassert(layout.storage.u.virt.list[layout.storage.u.virt.list_nused].virtual_select == NULL);
+    } /* end if */
+
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pset_virtual() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_virtual_count
+ *
+ * Purpose:     VDSINC
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Neil Fortner
+ *              Friday, February  13, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_virtual_count(hid_t dcpl_id, size_t *count/*out*/)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    H5O_layout_t layout;        /* Layout information */
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ix", dcpl_id, count);
+    HDassert(0 && "checking code coverage...");//VDSINC
+
+    if(count) {
+        /* Get the plist structure */
+        if(NULL == (plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
+            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+        /* Retrieve the layout property */
+        if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &layout) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't get layout")
+        if(H5D_VIRTUAL != layout.type)
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a virtual storage layout")
+
+        /* Return the number of mappings  */
+        *count = layout.storage.u.virt.list_nused;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_virtual_count() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_virtual_vspace
+ *
+ * Purpose:     VDSINC
+ *
+ * Return:      VDSINC
+ *
+ * Programmer:  Neil Fortner
+ *              Friday, February  13, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Pget_virtual_vspace(hid_t dcpl_id, size_t index)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    H5O_layout_t layout;        /* Layout information */
+    H5S_t *space;               /* Dataspace pointer */
+    hid_t ret_value;            /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("i", "iz", dcpl_id, index);
+    HDassert(0 && "checking code coverage...");//VDSINC
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Retrieve the layout property */
+    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &layout) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't get layout")
+    if(H5D_VIRTUAL != layout.type)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a virtual storage layout")
+
+    /* Get the virtual space */
+    if(index >= layout.storage.u.virt.list_nalloc)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, FAIL, "invalid index (out of range)")
+    if(NULL == (space = H5S_copy(layout.storage.u.virt.list[index].virtual_select, FALSE, TRUE)))
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTCOPY, FAIL, "unable to copy virtual selection")
+
+    /* Register ID */
+    if((ret_value = H5I_register(H5I_DATASPACE, space, TRUE)) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register data space")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_virtual_vspace() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_virtual_srcspace
+ *
+ * Purpose:     VDSINC
+ *
+ * Return:      VDSINC
+ *
+ * Programmer:  Neil Fortner
+ *              Saturday, February  14, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Pget_virtual_srcspace(hid_t dcpl_id, size_t index)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    H5O_layout_t layout;        /* Layout information */
+    H5S_t *space;               /* Dataspace pointer */
+    hid_t ret_value;            /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("i", "iz", dcpl_id, index);
+    HDassert(0 && "checking code coverage...");//VDSINC
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Retrieve the layout property */
+    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &layout) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't get layout")
+    if(H5D_VIRTUAL != layout.type)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a virtual storage layout")
+
+    /* Get the virtual space */
+    if(index >= layout.storage.u.virt.list_nalloc)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, FAIL, "invalid index (out of range)")
+    if(NULL == (space = H5S_copy(layout.storage.u.virt.list[index].source_select, FALSE, TRUE)))
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTCOPY, FAIL, "unable to copy source selection")
+
+    /* Register ID */
+    if((ret_value = H5I_register(H5I_DATASPACE, space, TRUE)) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register data space")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_virtual_srcspace() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_virtual_filename
+ *
+ * Purpose:     VDSINC
+ *
+ * Return:      VDSINC
+ *
+ * Programmer:  Neil Fortner
+ *              Saturday, February  14, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+ssize_t
+H5Pget_virtual_filename(hid_t dcpl_id, size_t index, char *name/*out*/,
+    size_t size)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    H5O_layout_t layout;        /* Layout information */
+    ssize_t ret_value;            /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE4("Zs", "izxz", dcpl_id, index, name, size);
+    HDassert(0 && "checking code coverage...");//VDSINC
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Retrieve the layout property */
+    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &layout) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't get layout")
+    if(H5D_VIRTUAL != layout.type)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a virtual storage layout")
+
+    /* Get the virtual filename */
+    HDassert(layout.storage.u.virt.list[index].source_file_name);
+    if(name && (size > 0))
+        (void)HDstrncpy(name, layout.storage.u.virt.list[index].source_file_name, size);
+    ret_value = (ssize_t)HDstrlen(layout.storage.u.virt.list[index].source_file_name);
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_virtual_filename() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_virtual_dsetname
+ *
+ * Purpose:     VDSINC
+ *
+ * Return:      VDSINC
+ *
+ * Programmer:  Neil Fortner
+ *              Saturday, February  14, 2015
+ *
+ *-------------------------------------------------------------------------
+ */
+ssize_t
+H5Pget_virtual_dsetname(hid_t dcpl_id, size_t index, char *name/*out*/,
+    size_t size)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    H5O_layout_t layout;        /* Layout information */
+    ssize_t ret_value;            /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE4("Zs", "izxz", dcpl_id, index, name, size);
+    HDassert(0 && "checking code coverage...");//VDSINC
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Retrieve the layout property */
+    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &layout) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't get layout")
+    if(H5D_VIRTUAL != layout.type)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a virtual storage layout")
+
+    /* Get the virtual filename */
+    HDassert(layout.storage.u.virt.list[index].source_dset_name);
+    if(name && (size > 0))
+        (void)HDstrncpy(name, layout.storage.u.virt.list[index].source_dset_name, size);
+    ret_value = (ssize_t)HDstrlen(layout.storage.u.virt.list[index].source_dset_name);
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_virtual_dsetname() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5Pset_external
  *
  * Purpose:	Adds an external file to the list of external files. PLIST_ID
@@ -2419,6 +2803,10 @@ H5Pset_alloc_time(hid_t plist_id, H5D_alloc_time_t alloc_time)
                 alloc_time = H5D_ALLOC_TIME_INCR;
                 break;
 
+            case H5D_VIRTUAL:
+                alloc_time = H5D_ALLOC_TIME_INCR;
+                break;
+
             case H5D_LAYOUT_ERROR:
             case H5D_NLAYOUTS:
             default:
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index f56692c..c1c6f17 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -354,6 +354,15 @@ H5_DLL herr_t H5Pset_layout(hid_t plist_id, H5D_layout_t layout);
 H5_DLL H5D_layout_t H5Pget_layout(hid_t plist_id);
 H5_DLL herr_t H5Pset_chunk(hid_t plist_id, int ndims, const hsize_t dim[/*ndims*/]);
 H5_DLL int H5Pget_chunk(hid_t plist_id, int max_ndims, hsize_t dim[]/*out*/);
+H5_DLL herr_t H5Pset_virtual(hid_t dcpl_id, hid_t vspace_id,
+    const char *src_file_name, const char *src_dset_name, hid_t src_space_id);
+H5_DLL herr_t H5Pget_virtual_count(hid_t dcpl_id, size_t *count/*out*/);
+H5_DLL hid_t H5Pget_virtual_vspace(hid_t dcpl_id, size_t index);
+H5_DLL hid_t H5Pget_virtual_srcspace(hid_t dcpl_id, size_t index);
+H5_DLL ssize_t H5Pget_virtual_filename(hid_t dcpl_id, size_t index,
+    char *name/*out*/, size_t size);
+H5_DLL ssize_t H5Pget_virtual_dsetname(hid_t dcpl_id, size_t index,
+    char *name/*out*/, size_t size);
 H5_DLL herr_t H5Pset_external(hid_t plist_id, const char *name, off_t offset,
           hsize_t size);
 H5_DLL int H5Pget_external_count(hid_t plist_id);
diff --git a/src/H5Sall.c b/src/H5Sall.c
index a9e72fb..6ac00d2 100644
--- a/src/H5Sall.c
+++ b/src/H5Sall.c
@@ -39,8 +39,8 @@ static herr_t H5S_all_get_seq_list(const H5S_t *space, unsigned flags,
 static herr_t H5S_all_release(H5S_t *space);
 static htri_t H5S_all_is_valid(const H5S_t *space);
 static hssize_t H5S_all_serial_size(const H5S_t *space);
-static herr_t H5S_all_serialize(const H5S_t *space, uint8_t *buf);
-static herr_t H5S_all_deserialize(H5S_t *space, const uint8_t *buf);
+static herr_t H5S_all_serialize(const H5S_t *space, uint8_t **p);
+static herr_t H5S_all_deserialize(H5S_t *space, const uint8_t **p);
 static herr_t H5S_all_bounds(const H5S_t *space, hsize_t *start, hsize_t *end);
 static herr_t H5S_all_offset(const H5S_t *space, hsize_t *off);
 static htri_t H5S_all_is_contiguous(const H5S_t *space);
@@ -496,9 +496,11 @@ H5S_all_serial_size (const H5S_t UNUSED *space)
  PURPOSE
     Serialize the current selection into a user-provided buffer.
  USAGE
-    herr_t H5S_all_serialize(space, buf)
-        H5S_t *space;           IN: Dataspace pointer of selection to serialize
-        uint8 *buf;             OUT: Buffer to put serialized selection into
+    herr_t H5S_all_serialize(space, p)
+        const H5S_t *space;     IN: Dataspace with selection to serialize
+        uint8_t **p;            OUT: Pointer to buffer to put serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -534,9 +536,12 @@ H5S_all_serialize (const H5S_t *space, uint8_t **p)
  PURPOSE
     Deserialize the current selection from a user-provided buffer.
  USAGE
-    herr_t H5S_all_deserialize(space, buf)
-        H5S_t *space;           IN/OUT: Dataspace pointer to place selection into
-        uint8 *buf;             IN: Buffer to retrieve serialized selection from
+    herr_t H5S_all_deserialize(space, p)
+        H5S_t *space;           IN/OUT: Dataspace pointer to place
+                                selection into
+        uint8 **p;              OUT: Pointer to buffer holding serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -548,9 +553,8 @@ H5S_all_serialize (const H5S_t *space, uint8_t **p)
  REVISION LOG
 --------------------------------------------------------------------------*/
 static herr_t
-H5S_all_deserialize(H5S_t **space, const uint8_t **p)
+H5S_all_deserialize(H5S_t *space, const uint8_t **p)
 {
-    H5S_t *tmp_space;
     herr_t ret_value = SUCCEED;   /* return value */
 
     FUNC_ENTER_NOAPI(FAIL)
@@ -559,31 +563,11 @@ H5S_all_deserialize(H5S_t **space, const uint8_t **p)
     HDassert(p);
     HDassert(*p);
 
-    /* Allocate space if not provided */
-    if(!*space) {
-        if(NULL == (tmp_space = H5S_create(H5S_SIMPLE)))
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create dataspace")
-    } /* end if */
-    else
-        tmp_space = *space;
-
-
-    /* Skip over the remainder of the header */
-    *p += 12;
-
     /* Change to "all" selection */
-    if(H5S_select_all(tmp_space, TRUE) < 0)
+    if(H5S_select_all(space, TRUE) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
 
-    if(!*space)
-        *space = tmp_space;
-
 done:
-    /* Free temporary space if not passed to caller (only happens on error) */
-    if(!*space && tmp_space)
-        if(H5S_close(tmp_space) < 0)
-            HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "can't close dataspace")
-
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* H5S_all_deserialize() */
 
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index 02d9359..91f31d2 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -54,8 +54,8 @@ static herr_t H5S_hyper_get_seq_list(const H5S_t *space, unsigned flags,
 static herr_t H5S_hyper_release(H5S_t *space);
 static htri_t H5S_hyper_is_valid(const H5S_t *space);
 static hssize_t H5S_hyper_serial_size(const H5S_t *space);
-static herr_t H5S_hyper_serialize(const H5S_t *space, uint8_t *buf);
-static herr_t H5S_hyper_deserialize(H5S_t *space, const uint8_t *buf);
+static herr_t H5S_hyper_serialize(const H5S_t *space, uint8_t **p);
+static herr_t H5S_hyper_deserialize(H5S_t *space, const uint8_t **p);
 static herr_t H5S_hyper_bounds(const H5S_t *space, hsize_t *start, hsize_t *end);
 static herr_t H5S_hyper_offset(const H5S_t *space, hsize_t *offset);
 static htri_t H5S_hyper_is_contiguous(const H5S_t *space);
@@ -2055,9 +2055,11 @@ done:
  PURPOSE
     Serialize the current selection into a user-provided buffer.
  USAGE
-    herr_t H5S_hyper_serialize(space, buf)
-        H5S_t *space;           IN: Dataspace pointer of selection to serialize
-        uint8 *buf;             OUT: Buffer to put serialized selection into
+    herr_t H5S_hyper_serialize(space, p)
+        const H5S_t *space;     IN: Dataspace with selection to serialize
+        uint8_t **p;            OUT: Pointer to buffer to put serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -2096,7 +2098,7 @@ H5S_hyper_serialize (const H5S_t *space, uint8_t **p)
     *p += 4;             /* skip over space for length */
 
     /* Encode number of dimensions */
-    UINT32ENCODE(buf, (uint32_t)space->extent.rank);
+    UINT32ENCODE(*p, (uint32_t)space->extent.rank);
     len += 4;
 
     /* Check for a "regular" hyperslab selection */
@@ -2197,7 +2199,7 @@ H5S_hyper_serialize (const H5S_t *space, uint8_t **p)
 
         /* Add 8 bytes times the rank for each hyperslab selected */
         H5_CHECK_OVERFLOW((8 * space->extent.rank * block_count), hsize_t, size_t);
-        len += (size_t)(8 * space->extent.rank * block_count);
+        len += (uint32_t)(8 * space->extent.rank * block_count);
 
         /* Encode each hyperslab in selection */
         H5S_hyper_serialize_helper(space->select.sel_info.hslab->span_lst, start, end, (hsize_t)0, p);
@@ -2216,9 +2218,12 @@ H5S_hyper_serialize (const H5S_t *space, uint8_t **p)
  PURPOSE
     Deserialize the current selection from a user-provided buffer.
  USAGE
-    herr_t H5S_hyper_deserialize(space, buf)
-        H5S_t *space;           IN/OUT: Dataspace pointer to place selection into
-        uint8 *buf;             IN: Buffer to retrieve serialized selection from
+    herr_t H5S_hyper_deserialize(space, p)
+        H5S_t *space;           IN/OUT: Dataspace pointer to place
+                                selection into
+        uint8 **p;              OUT: Pointer to buffer holding serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -2230,10 +2235,9 @@ H5S_hyper_serialize (const H5S_t *space, uint8_t **p)
  REVISION LOG
 --------------------------------------------------------------------------*/
 static herr_t
-H5S_hyper_deserialize (H5S_t **space, const uint8_t **p)
+H5S_hyper_deserialize (H5S_t *space, const uint8_t **p)
 {
-    H5S_t *tmp_space;
-    uint32_t rank;           	/* rank of points */
+    unsigned rank;           	/* rank of points */
     size_t num_elem=0;      	/* number of elements in selection */
     hsize_t start[H5O_LAYOUT_NDIMS];	/* hyperslab start information */
     hsize_t end[H5O_LAYOUT_NDIMS];	/* hyperslab end information */
@@ -2256,26 +2260,10 @@ H5S_hyper_deserialize (H5S_t **space, const uint8_t **p)
     HDassert(*p);
 
     /* Deserialize slabs to select */
-    *p+=12;    /* Skip over remainder of selection header */
-    UINT32DECODE(*p,rank);  /* decode the rank of the point selection */
+    /* The header and rank have already beed decoded */
+    rank = space->extent.rank;  /* Retrieve rank from space */
     UINT32DECODE(*p,num_elem);  /* decode the number of points */
 
-    /* Allocate space if not provided */
-    if(!*space) {
-        if(NULL == (tmp_space = H5S_create(H5S_SIMPLE)))
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create dataspace")
-
-        /* Set rank of dataspace */
-        tmp_space->extent.rank = rank;
-    } /* end if */
-    else {
-        tmp_space = *space;
-
-        /* Verify rank of dataspace */
-        if(rank!=tmp_space->extent.rank)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "rank of pointer does not match dataspace")
-    } /* end else */
-
     /* Set the count & stride for all blocks */
     for(tcount=count,tstride=stride,j=0; j<rank; j++,tstride++,tcount++) {
         *tcount=1;
@@ -2293,23 +2281,15 @@ H5S_hyper_deserialize (H5S_t **space, const uint8_t **p)
             UINT32DECODE(*p, *tend);
 
         /* Change the ending points into blocks */
-        for(tblock=block,tstart=start,tend=end,j=0; j<(unsigned)rank; j++,tstart++,tend++,tblock++)
+        for(tblock=block,tstart=start,tend=end,j=0; j<rank; j++,tstart++,tend++,tblock++)
             *tblock=(*tend-*tstart)+1;
 
         /* Select or add the hyperslab to the current selection */
-        if((ret_value=H5S_select_hyperslab(tmp_space,(i==0 ? H5S_SELECT_SET : H5S_SELECT_OR),start,stride,count,block))<0)
+        if((ret_value=H5S_select_hyperslab(space,(i==0 ? H5S_SELECT_SET : H5S_SELECT_OR),start,stride,count,block))<0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
     } /* end for */
 
-    if(!*space)
-        *space = tmp_space;
-
 done:
-    /* Free temporary space if not passed to caller (only happens on error) */
-    if(!*space && tmp_space)
-        if(H5S_close(tmp_space) < 0)
-            HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "can't close dataspace")
-
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* H5S_hyper_deserialize() */
 
diff --git a/src/H5Snone.c b/src/H5Snone.c
index a6c870a..94d41a9 100644
--- a/src/H5Snone.c
+++ b/src/H5Snone.c
@@ -40,8 +40,8 @@ static herr_t H5S_none_get_seq_list(const H5S_t *space, unsigned flags,
 static herr_t H5S_none_release(H5S_t *space);
 static htri_t H5S_none_is_valid(const H5S_t *space);
 static hssize_t H5S_none_serial_size(const H5S_t *space);
-static herr_t H5S_none_serialize(const H5S_t *space, uint8_t *buf);
-static herr_t H5S_none_deserialize(H5S_t *space, const uint8_t *buf);
+static herr_t H5S_none_serialize(const H5S_t *space, uint8_t **p);
+static herr_t H5S_none_deserialize(H5S_t *space, const uint8_t **p);
 static herr_t H5S_none_bounds(const H5S_t *space, hsize_t *start, hsize_t *end);
 static herr_t H5S_none_offset(const H5S_t *space, hsize_t *off);
 static htri_t H5S_none_is_contiguous(const H5S_t *space);
@@ -464,9 +464,11 @@ H5S_none_serial_size(const H5S_t UNUSED *space)
  PURPOSE
     Serialize the current selection into a user-provided buffer.
  USAGE
-    herr_t H5S_none_serialize(space, buf)
-        H5S_t *space;           IN: Dataspace pointer of selection to serialize
-        uint8 *buf;             OUT: Buffer to put serialized selection into
+    herr_t H5S_none_serialize(space, p)
+        const H5S_t *space;     IN: Dataspace with selection to serialize
+        uint8_t **p;            OUT: Pointer to buffer to put serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -500,9 +502,12 @@ H5S_none_serialize(const H5S_t *space, uint8_t **p)
  PURPOSE
     Deserialize the current selection from a user-provided buffer.
  USAGE
-    herr_t H5S_none_deserialize(space, buf)
-        H5S_t *space;           IN/OUT: Dataspace pointer to place selection into
-        uint8 *buf;             IN: Buffer to retrieve serialized selection from
+    herr_t H5S_none_deserialize(space, p)
+        H5S_t *space;           IN/OUT: Dataspace pointer to place
+                                selection into
+        uint8 **p;              OUT: Pointer to buffer holding serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -514,9 +519,8 @@ H5S_none_serialize(const H5S_t *space, uint8_t **p)
  REVISION LOG
 --------------------------------------------------------------------------*/
 static herr_t
-H5S_none_deserialize(H5S_t **space, const uint8_t **p)
+H5S_none_deserialize(H5S_t *space, const uint8_t **p)
 {
-    H5S_t *tmp_space;
     herr_t ret_value = SUCCEED;  /* return value */
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -525,30 +529,11 @@ H5S_none_deserialize(H5S_t **space, const uint8_t **p)
     HDassert(p);
     HDassert(*p);
 
-    /* Allocate space if not provided */
-    if(!*space) {
-        if(NULL == (tmp_space = H5S_create(H5S_SIMPLE)))
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create dataspace")
-    } /* end if */
-    else
-        tmp_space = *space;
-
-    /* Skip over the remainder of the header */
-    *p += 12;
-
     /* Change to "none" selection */
-    if(H5S_select_none(tmp_space) < 0)
+    if(H5S_select_none(space) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
 
-    if(!*space)
-        *space = tmp_space;
-
 done:
-    /* Free temporary space if not passed to caller (only happens on error) */
-    if(!*space && tmp_space)
-        if(H5S_close(tmp_space) < 0)
-            HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "can't close dataspace")
-
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* H5S_none_deserialize() */
 
diff --git a/src/H5Spkg.h b/src/H5Spkg.h
index 91f3ed1..5f84717 100644
--- a/src/H5Spkg.h
+++ b/src/H5Spkg.h
@@ -130,9 +130,9 @@ typedef htri_t (*H5S_sel_is_valid_func_t)(const H5S_t *space);
 /* Method to determine number of bytes required to store current selection */
 typedef hssize_t (*H5S_sel_serial_size_func_t)(const H5S_t *space);
 /* Method to store current selection in "serialized" form (a byte sequence suitable for storing on disk) */
-typedef herr_t (*H5S_sel_serialize_func_t)(const H5S_t *space, uint8_t *buf);
+typedef herr_t (*H5S_sel_serialize_func_t)(const H5S_t *space, uint8_t **p);
 /* Method to store create selection from "serialized" form (a byte sequence suitable for storing on disk) */
-typedef herr_t (*H5S_sel_deserialize_func_t)(H5S_t **space, const uint8_t **p);
+typedef herr_t (*H5S_sel_deserialize_func_t)(H5S_t *space, const uint8_t **p);
 /* Method to determine smallest n-D bounding box containing the current selection */
 typedef herr_t (*H5S_sel_bounds_func_t)(const H5S_t *space, hsize_t *start, hsize_t *end);
 /* Method to determine linear offset of initial element in selection within dataspace */
diff --git a/src/H5Spoint.c b/src/H5Spoint.c
index e55834d..e6a4a39 100644
--- a/src/H5Spoint.c
+++ b/src/H5Spoint.c
@@ -41,8 +41,8 @@ static herr_t H5S_point_get_seq_list(const H5S_t *space, unsigned flags,
 static herr_t H5S_point_release(H5S_t *space);
 static htri_t H5S_point_is_valid(const H5S_t *space);
 static hssize_t H5S_point_serial_size(const H5S_t *space);
-static herr_t H5S_point_serialize(const H5S_t *space, uint8_t *buf);
-static herr_t H5S_point_deserialize(H5S_t *space, const uint8_t *buf);
+static herr_t H5S_point_serialize(const H5S_t *space, uint8_t **p);
+static herr_t H5S_point_deserialize(H5S_t *space, const uint8_t **p);
 static herr_t H5S_point_bounds(const H5S_t *space, hsize_t *start, hsize_t *end);
 static herr_t H5S_point_offset(const H5S_t *space, hsize_t *off);
 static htri_t H5S_point_is_contiguous(const H5S_t *space);
@@ -804,9 +804,11 @@ H5S_point_serial_size (const H5S_t *space)
  PURPOSE
     Serialize the current selection into a user-provided buffer.
  USAGE
-    herr_t H5S_point_serialize(space, buf)
-        H5S_t *space;           IN: Dataspace pointer of selection to serialize
-        uint8 *buf;             OUT: Buffer to put serialized selection into
+    herr_t H5S_point_serialize(space, p)
+        const H5S_t *space;     IN: Dataspace with selection to serialize
+        uint8_t **p;            OUT: Pointer to buffer to put serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -848,7 +850,7 @@ H5S_point_serialize (const H5S_t *space, uint8_t **p)
     curr=space->select.sel_info.pnt_lst->head;
     while(curr!=NULL) {
         /* Add 4 bytes times the rank for each element selected */
-        *p+=4*space->extent.rank;
+        len+=4*space->extent.rank;
 
         /* Encode each point */
         for(u=0; u<space->extent.rank; u++)
@@ -870,9 +872,12 @@ H5S_point_serialize (const H5S_t *space, uint8_t **p)
  PURPOSE
     Deserialize the current selection from a user-provided buffer.
  USAGE
-    herr_t H5S_point_deserialize(space, buf)
-        H5S_t *space;           IN/OUT: Dataspace pointer to place selection into
-        uint8 *buf;             IN: Buffer to retrieve serialized selection from
+    herr_t H5S_point_deserialize(space, p)
+        H5S_t *space;           IN/OUT: Dataspace pointer to place
+                                selection into
+        uint8 **p;              OUT: Pointer to buffer holding serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -884,11 +889,10 @@ H5S_point_serialize (const H5S_t *space, uint8_t **p)
  REVISION LOG
 --------------------------------------------------------------------------*/
 static herr_t
-H5S_point_deserialize (H5S_t **space, const uint8_t **p)
+H5S_point_deserialize (H5S_t *space, const uint8_t **p)
 {
-    H5S_t *tmp_space;
     H5S_seloper_t op=H5S_SELECT_SET;    /* Selection operation */
-    uint32_t rank;           /* Rank of points */
+    unsigned rank;          /* Rank of points */
     size_t num_elem=0;      /* Number of elements in selection */
     hsize_t *coord=NULL, *tcoord;   /* Pointer to array of elements */
     unsigned i, j;              /* local counting variables */
@@ -902,25 +906,9 @@ H5S_point_deserialize (H5S_t **space, const uint8_t **p)
     HDassert(*p);
 
     /* Deserialize points to select */
-    *p += 12;    /* Skip over remaining selection header */
-    UINT32DECODE(*p, rank);  /* decode the rank of the point selection */
-    UINT32DECODE(*p, num_elem);  /* decode the number of points */
-
-    /* Allocate space if not provided */
-    if(!*space) {
-        if(NULL == (tmp_space = H5S_create(H5S_SIMPLE)))
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create dataspace")
-
-        /* Set rank of dataspace */
-        tmp_space->extent.rank = rank;
-    } /* end if */
-    else {
-        tmp_space = *space;
-
-        /* Verify rank of dataspace */
-        if(rank!=tmp_space->extent.rank)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "rank of pointer does not match dataspace")
-    } /* end else */
+    /* The header and rank have already beed decoded */
+    rank = space->extent.rank;  /* Retrieve rank from space */
+    UINT32DECODE(*p, num_elem); /* decode the number of points */
 
     /* Allocate space for the coordinates */
     if(NULL == (coord = (hsize_t *)H5MM_malloc(num_elem * rank * sizeof(hsize_t))))
@@ -932,18 +920,10 @@ H5S_point_deserialize (H5S_t **space, const uint8_t **p)
             UINT32DECODE(*p, *tcoord);
 
     /* Select points */
-    if(H5S_select_elements(tmp_space, op, num_elem, (const hsize_t *)coord) < 0)
+    if(H5S_select_elements(space, op, num_elem, (const hsize_t *)coord) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
 
-    if(!*space)
-        *space = tmp_space;
-
 done:
-    /* Free temporary space if not passed to caller (only happens on error) */
-    if(!*space && tmp_space)
-        if(H5S_close(tmp_space) < 0)
-            HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "can't close dataspace")
-
     /* Free the coordinate array if necessary */
     if(coord != NULL)
         H5MM_xfree(coord);
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 44cd6c3..7b7b8c6 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -206,7 +206,7 @@ H5_DLL int H5S_extent_get_dims(const H5S_extent_t *ext, hsize_t dims[], hsize_t
 H5_DLL htri_t H5S_extent_equal(const H5S_t *ds1, const H5S_t *ds2);
 
 /* Operations on selections */
-H5_DLL herr_t H5S_select_deserialize(H5S_t *space, const uint8_t *buf);
+H5_DLL herr_t H5S_select_deserialize(H5S_t **space, const uint8_t **p);
 H5_DLL H5S_sel_type H5S_get_select_type(const H5S_t *space);
 H5_DLL herr_t H5S_select_iterate(void *buf, hid_t type_id, const H5S_t *space,
     H5D_operator_t op, void *operator_data);
@@ -227,7 +227,7 @@ H5_DLL herr_t H5S_select_get_seq_list(const H5S_t *space, unsigned flags,
     H5S_sel_iter_t *iter, size_t maxseq, size_t maxbytes,
     size_t *nseq, size_t *nbytes, hsize_t *off, size_t *len);
 H5_DLL hssize_t H5S_select_serial_size(const H5S_t *space);
-H5_DLL herr_t H5S_select_serialize(const H5S_t *space, uint8_t *buf);
+H5_DLL herr_t H5S_select_serialize(const H5S_t *space, uint8_t **p);
 H5_DLL htri_t H5S_select_is_contiguous(const H5S_t *space);
 H5_DLL htri_t H5S_select_is_single(const H5S_t *space);
 H5_DLL htri_t H5S_select_is_regular(const H5S_t *space);
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index 7d22f08..34e9473 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -239,9 +239,11 @@ H5S_select_serial_size(const H5S_t *space)
  PURPOSE
     Serialize the selection for a dataspace into a buffer
  USAGE
-    herr_t H5S_select_serialize(space, buf)
+    herr_t H5S_select_serialize(space, p)
         const H5S_t *space;     IN: Dataspace with selection to serialize
-        uint8_t **p;            OUT: Buffer to put serialized selection
+        uint8_t **p;            OUT: Pointer to buffer to put serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -263,7 +265,7 @@ H5S_select_serialize(const H5S_t *space, uint8_t **p)
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
     HDassert(space);
-    HDassert(buf);
+    HDassert(p);
 
     /* Call the selection type's serialize function */
     ret_value=(*space->select.type->serialize)(space,p);
@@ -428,9 +430,13 @@ H5S_select_valid(const H5S_t *space)
     Deserialize the current selection from a user-provided buffer into a real
         selection in the dataspace.
  USAGE
-    herr_t H5S_select_deserialize(space, buf)
-        H5S_t *space;           IN/OUT: Dataspace pointer to place selection into
-        uint8 *buf;             IN: Buffer to retrieve serialized selection from
+    herr_t H5S_select_deserialize(space, p)
+        H5S_t **space;          IN/OUT: Dataspace pointer to place
+                                selection into.  Will be allocated if not
+                                provided.
+        uint8 **p;              OUT: Pointer to buffer holding serialized
+                                selection.  Will be advanced to end of
+                                serialized selection.
  RETURNS
     Non-negative on success/Negative on failure
  DESCRIPTION
@@ -446,38 +452,78 @@ H5S_select_valid(const H5S_t *space)
 herr_t
 H5S_select_deserialize (H5S_t **space, const uint8_t **p)
 {
-    uint32_t sel_type;       /* Pointer to the selection type */
+    H5S_t *tmp_space;       /* Pointer to actual dataspace to use, either
+                               *space or a newly allocated one */
+    uint32_t sel_type;      /* Pointer to the selection type */
     herr_t ret_value=FAIL;  /* return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
     HDassert(space);
 
+    /* Allocate space if not provided */
+    if(!*space) {
+        if(NULL == (tmp_space = H5S_create(H5S_SIMPLE)))
+            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create dataspace")
+    } /* end if */
+    else
+        tmp_space = *space;
+
+    /* Decode selection type */
     UINT32DECODE(*p, sel_type);
+
+    /* Skip over the remainder of the header */
+    *p += 12;
+
+    /* Decode and check or patch rank for point and hyperslab selections */
+    if((sel_type == H5S_SEL_POINTS) || (sel_type == H5S_SEL_HYPERSLABS)) {
+        uint32_t rank;              /* Rank of dataspace */
+
+        /* Decode the rank of the point selection */
+        UINT32DECODE(*p,rank);
+
+        if(!*space)
+            /* Patch the rank of the allocated dataspace */
+            tmp_space->extent.rank = rank;
+        else
+            /* Verify the rank of the provided dataspace */
+            if(rank != tmp_space->extent.rank)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "rank of serialized selection does not match dataspace")
+    } /* end if */
+
+    /* Make routine for selection type */
     switch(sel_type) {
         case H5S_SEL_POINTS:         /* Sequence of points selected */
-            ret_value=(*H5S_sel_point->deserialize)(space,p);
+            ret_value = (*H5S_sel_point->deserialize)(tmp_space, p);
             break;
 
         case H5S_SEL_HYPERSLABS:     /* Hyperslab selection defined */
-            ret_value=(*H5S_sel_hyper->deserialize)(space,p);
+            ret_value = (*H5S_sel_hyper->deserialize)(tmp_space, p);
             break;
 
         case H5S_SEL_ALL:            /* Entire extent selected */
-            ret_value=(*H5S_sel_all->deserialize)(space,p);
+            ret_value = (*H5S_sel_all->deserialize)(tmp_space, p);
             break;
 
         case H5S_SEL_NONE:           /* Nothing selected */
-            ret_value=(*H5S_sel_none->deserialize)(space,p);
+            ret_value = (*H5S_sel_none->deserialize)(tmp_space, p);
             break;
 
         default:
             break;
     }
-    if(ret_value<0)
+    if(ret_value < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTLOAD, FAIL, "can't deserialize selection")
 
+    /* Return space to the caller if allocated */
+    if(!*space)
+        *space = tmp_space;
 done:
+    /* Free temporary space if not passed to caller (only happens on error) */
+    if(!*space && tmp_space)
+        if(H5S_close(tmp_space) < 0)
+            HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "can't close dataspace")
+
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* H5S_select_deserialize() */
 
diff --git a/src/H5trace.c b/src/H5trace.c
index 3a84489..08641da 100644
--- a/src/H5trace.c
+++ b/src/H5trace.c
@@ -524,6 +524,10 @@ H5_trace(const double *returning, const char *func, const char *type, ...)
                                     fprintf(out, "H5D_CHUNKED");
                                     break;
 
+                                case H5D_VIRTUAL:
+                                    fprintf(out, "H5D_VIRTUAL");
+                                    break;
+
                                 case H5D_NLAYOUTS:
                                     fprintf(out, "H5D_NLAYOUTS");
                                     break;
diff --git a/src/Makefile.in b/src/Makefile.in
index 1933734..14ed2af 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -155,50 +155,51 @@ am_libhdf5_la_OBJECTS = H5.lo H5checksum.lo H5dbg.lo H5system.lo \
 	H5Dbtree.lo H5Dchunk.lo H5Dcompact.lo H5Dcontig.lo H5Ddbg.lo \
 	H5Ddeprec.lo H5Defl.lo H5Dfill.lo H5Dint.lo H5Dio.lo \
 	H5Dlayout.lo H5Dmpio.lo H5Doh.lo H5Dscatgath.lo H5Dselect.lo \
-	H5Dtest.lo H5E.lo H5Edeprec.lo H5Eint.lo H5EA.lo H5EAcache.lo \
-	H5EAdbg.lo H5EAdblkpage.lo H5EAdblock.lo H5EAhdr.lo \
-	H5EAiblock.lo H5EAint.lo H5EAsblock.lo H5EAstat.lo H5EAtest.lo \
-	H5F.lo H5Fint.lo H5Faccum.lo H5Fcwfs.lo H5Fdbg.lo H5Fdeprec.lo \
-	H5Fefc.lo H5Ffake.lo H5Fio.lo H5Fmount.lo H5Fmpi.lo \
-	H5Fquery.lo H5Fsfile.lo H5Fsuper.lo H5Fsuper_cache.lo \
-	H5Ftest.lo H5FA.lo H5FAcache.lo H5FAdbg.lo H5FAdblock.lo \
-	H5FAdblkpage.lo H5FAhdr.lo H5FAstat.lo H5FAtest.lo H5FD.lo \
-	H5FDcore.lo H5FDdirect.lo H5FDfamily.lo H5FDint.lo H5FDlog.lo \
-	H5FDmpi.lo H5FDmpio.lo H5FDmulti.lo H5FDsec2.lo H5FDspace.lo \
-	H5FDstdio.lo H5FL.lo H5FO.lo H5FS.lo H5FScache.lo H5FSdbg.lo \
-	H5FSsection.lo H5FSstat.lo H5FStest.lo H5G.lo H5Gbtree2.lo \
-	H5Gcache.lo H5Gcompact.lo H5Gdense.lo H5Gdeprec.lo H5Gent.lo \
-	H5Gint.lo H5Glink.lo H5Gloc.lo H5Gname.lo H5Gnode.lo H5Gobj.lo \
-	H5Goh.lo H5Groot.lo H5Gstab.lo H5Gtest.lo H5Gtraverse.lo \
-	H5HF.lo H5HFbtree2.lo H5HFcache.lo H5HFdbg.lo H5HFdblock.lo \
-	H5HFdtable.lo H5HFhdr.lo H5HFhuge.lo H5HFiblock.lo H5HFiter.lo \
-	H5HFman.lo H5HFsection.lo H5HFspace.lo H5HFstat.lo H5HFtest.lo \
-	H5HFtiny.lo H5HG.lo H5HGcache.lo H5HGdbg.lo H5HGquery.lo \
-	H5HL.lo H5HLcache.lo H5HLdbg.lo H5HLint.lo H5HP.lo H5I.lo \
-	H5Itest.lo H5L.lo H5Lexternal.lo H5lib_settings.lo H5MF.lo \
-	H5MFaggr.lo H5MFdbg.lo H5MFsection.lo H5MM.lo H5MP.lo \
-	H5MPtest.lo H5O.lo H5Oainfo.lo H5Oalloc.lo H5Oattr.lo \
-	H5Oattribute.lo H5Obogus.lo H5Obtreek.lo H5Ocache.lo \
-	H5Ochunk.lo H5Ocont.lo H5Ocopy.lo H5Odbg.lo H5Odrvinfo.lo \
-	H5Odtype.lo H5Oefl.lo H5Ofill.lo H5Ofsinfo.lo H5Oginfo.lo \
-	H5Olayout.lo H5Olinfo.lo H5Olink.lo H5Omessage.lo H5Omtime.lo \
-	H5Oname.lo H5Onull.lo H5Opline.lo H5Orefcount.lo H5Osdspace.lo \
-	H5Oshared.lo H5Ostab.lo H5Oshmesg.lo H5Otest.lo H5Ounknown.lo \
-	H5P.lo H5Pacpl.lo H5Pdapl.lo H5Pdcpl.lo H5Pdeprec.lo \
-	H5Pdxpl.lo H5Pencdec.lo H5Pfapl.lo H5Pfcpl.lo H5Pfmpl.lo \
-	H5Pgcpl.lo H5Pint.lo H5Plapl.lo H5Plcpl.lo H5Pocpl.lo \
-	H5Pocpypl.lo H5Pstrcpl.lo H5Ptest.lo H5PL.lo H5R.lo \
-	H5Rdeprec.lo H5UC.lo H5RS.lo H5S.lo H5Sall.lo H5Sdbg.lo \
-	H5Shyper.lo H5Smpio.lo H5Snone.lo H5Spoint.lo H5Sselect.lo \
-	H5Stest.lo H5SL.lo H5SM.lo H5SMbtree2.lo H5SMcache.lo \
-	H5SMmessage.lo H5SMtest.lo H5ST.lo H5T.lo H5Tarray.lo \
-	H5Tbit.lo H5Tcommit.lo H5Tcompound.lo H5Tconv.lo H5Tcset.lo \
-	H5Tdbg.lo H5Tdeprec.lo H5Tenum.lo H5Tfields.lo H5Tfixed.lo \
-	H5Tfloat.lo H5Tinit.lo H5Tnative.lo H5Toffset.lo H5Toh.lo \
-	H5Topaque.lo H5Torder.lo H5Tpad.lo H5Tprecis.lo H5Tstrpad.lo \
-	H5Tvisit.lo H5Tvlen.lo H5TS.lo H5VM.lo H5WB.lo H5Z.lo \
-	H5Zdeflate.lo H5Zfletcher32.lo H5Znbit.lo H5Zshuffle.lo \
-	H5Zszip.lo H5Zscaleoffset.lo H5Ztrans.lo
+	H5Dtest.lo H5Dvirtual.lo H5E.lo H5Edeprec.lo H5Eint.lo H5EA.lo \
+	H5EAcache.lo H5EAdbg.lo H5EAdblkpage.lo H5EAdblock.lo \
+	H5EAhdr.lo H5EAiblock.lo H5EAint.lo H5EAsblock.lo H5EAstat.lo \
+	H5EAtest.lo H5F.lo H5Fint.lo H5Faccum.lo H5Fcwfs.lo H5Fdbg.lo \
+	H5Fdeprec.lo H5Fefc.lo H5Ffake.lo H5Fio.lo H5Fmount.lo \
+	H5Fmpi.lo H5Fquery.lo H5Fsfile.lo H5Fsuper.lo \
+	H5Fsuper_cache.lo H5Ftest.lo H5FA.lo H5FAcache.lo H5FAdbg.lo \
+	H5FAdblock.lo H5FAdblkpage.lo H5FAhdr.lo H5FAstat.lo \
+	H5FAtest.lo H5FD.lo H5FDcore.lo H5FDdirect.lo H5FDfamily.lo \
+	H5FDint.lo H5FDlog.lo H5FDmpi.lo H5FDmpio.lo H5FDmulti.lo \
+	H5FDsec2.lo H5FDspace.lo H5FDstdio.lo H5FL.lo H5FO.lo H5FS.lo \
+	H5FScache.lo H5FSdbg.lo H5FSsection.lo H5FSstat.lo H5FStest.lo \
+	H5G.lo H5Gbtree2.lo H5Gcache.lo H5Gcompact.lo H5Gdense.lo \
+	H5Gdeprec.lo H5Gent.lo H5Gint.lo H5Glink.lo H5Gloc.lo \
+	H5Gname.lo H5Gnode.lo H5Gobj.lo H5Goh.lo H5Groot.lo H5Gstab.lo \
+	H5Gtest.lo H5Gtraverse.lo H5HF.lo H5HFbtree2.lo H5HFcache.lo \
+	H5HFdbg.lo H5HFdblock.lo H5HFdtable.lo H5HFhdr.lo H5HFhuge.lo \
+	H5HFiblock.lo H5HFiter.lo H5HFman.lo H5HFsection.lo \
+	H5HFspace.lo H5HFstat.lo H5HFtest.lo H5HFtiny.lo H5HG.lo \
+	H5HGcache.lo H5HGdbg.lo H5HGquery.lo H5HL.lo H5HLcache.lo \
+	H5HLdbg.lo H5HLint.lo H5HP.lo H5I.lo H5Itest.lo H5L.lo \
+	H5Lexternal.lo H5lib_settings.lo H5MF.lo H5MFaggr.lo \
+	H5MFdbg.lo H5MFsection.lo H5MM.lo H5MP.lo H5MPtest.lo H5O.lo \
+	H5Oainfo.lo H5Oalloc.lo H5Oattr.lo H5Oattribute.lo H5Obogus.lo \
+	H5Obtreek.lo H5Ocache.lo H5Ochunk.lo H5Ocont.lo H5Ocopy.lo \
+	H5Odbg.lo H5Odrvinfo.lo H5Odtype.lo H5Oefl.lo H5Ofill.lo \
+	H5Ofsinfo.lo H5Oginfo.lo H5Olayout.lo H5Olinfo.lo H5Olink.lo \
+	H5Omessage.lo H5Omtime.lo H5Oname.lo H5Onull.lo H5Opline.lo \
+	H5Orefcount.lo H5Osdspace.lo H5Oshared.lo H5Ostab.lo \
+	H5Oshmesg.lo H5Otest.lo H5Ounknown.lo H5P.lo H5Pacpl.lo \
+	H5Pdapl.lo H5Pdcpl.lo H5Pdeprec.lo H5Pdxpl.lo H5Pencdec.lo \
+	H5Pfapl.lo H5Pfcpl.lo H5Pfmpl.lo H5Pgcpl.lo H5Pint.lo \
+	H5Plapl.lo H5Plcpl.lo H5Pocpl.lo H5Pocpypl.lo H5Pstrcpl.lo \
+	H5Ptest.lo H5PL.lo H5R.lo H5Rdeprec.lo H5UC.lo H5RS.lo H5S.lo \
+	H5Sall.lo H5Sdbg.lo H5Shyper.lo H5Smpio.lo H5Snone.lo \
+	H5Spoint.lo H5Sselect.lo H5Stest.lo H5SL.lo H5SM.lo \
+	H5SMbtree2.lo H5SMcache.lo H5SMmessage.lo H5SMtest.lo H5ST.lo \
+	H5T.lo H5Tarray.lo H5Tbit.lo H5Tcommit.lo H5Tcompound.lo \
+	H5Tconv.lo H5Tcset.lo H5Tdbg.lo H5Tdeprec.lo H5Tenum.lo \
+	H5Tfields.lo H5Tfixed.lo H5Tfloat.lo H5Tinit.lo H5Tnative.lo \
+	H5Toffset.lo H5Toh.lo H5Topaque.lo H5Torder.lo H5Tpad.lo \
+	H5Tprecis.lo H5Tstrpad.lo H5Tvisit.lo H5Tvlen.lo H5TS.lo \
+	H5VM.lo H5WB.lo H5Z.lo H5Zdeflate.lo H5Zfletcher32.lo \
+	H5Znbit.lo H5Zshuffle.lo H5Zszip.lo H5Zscaleoffset.lo \
+	H5Ztrans.lo
 libhdf5_la_OBJECTS = $(am_libhdf5_la_OBJECTS)
 AM_V_lt = $(am__v_lt_@AM_V@)
 am__v_lt_ = $(am__v_lt_@AM_DEFAULT_V@)
@@ -756,7 +757,7 @@ libhdf5_la_SOURCES = H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5D.c H5Dbtree.c H5Dchunk.c H5Dcompact.c H5Dcontig.c H5Ddbg.c \
         H5Ddeprec.c H5Defl.c H5Dfill.c H5Dint.c \
         H5Dio.c H5Dlayout.c \
-        H5Dmpio.c H5Doh.c H5Dscatgath.c H5Dselect.c H5Dtest.c \
+        H5Dmpio.c H5Doh.c H5Dscatgath.c H5Dselect.c H5Dtest.c H5Dvirtual.c \
         H5E.c H5Edeprec.c H5Eint.c \
         H5EA.c H5EAcache.c H5EAdbg.c H5EAdblkpage.c H5EAdblock.c H5EAhdr.c \
         H5EAiblock.c H5EAint.c H5EAsblock.c H5EAstat.c H5EAtest.c \
@@ -1007,6 +1008,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Dscatgath.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Dselect.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Dtest.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Dvirtual.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5E.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5EA.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5EAcache.Plo@am__quote@